1. Technical Field
The present invention relates to an inkjet printer that has a cap to cover the ink nozzle face of the inkjet head, and a moisture supply mechanism that supplies a moisturizing fluid into the cap.
2. Related Art
In order to prevent an increase in the viscosity of ink in the ink nozzles from clogging the ink nozzles, inkjet printers cover the ink nozzle face in which the ink nozzles are formed with a cap while the inkjet head is at the maintenance position to suppress evaporation of moisture from the ink nozzles. A flushing operation that ejects ink from the ink nozzles into the cap while the cap is opposite the ink nozzle face is also regularly performed to suppress nozzle clogging. When ink nozzle clogging occurs, an ink suction operation that covers the ink nozzle face with a cap, produces negative pressure in the sealed space formed between the nozzle face and the cap by means of a suction pump, and forcibly expels ink from the ink nozzles into the cap, is performed to eliminate the clogging. The ink expelled from the ink nozzles in the flushing operation and ink suction operation is absorbed by an ink-absorbent material (referred to below as a sponge) such as felt held inside the cap.
A humectant such as glycerin is contained in the ink that is ejected from the ink nozzles, and as the flushing operation and ink suction operation are performed, the humectant accumulates in the sponge inside the cap. If moisture then evaporates from inside the cap and the balance between the moisture in the cap and the amount of humectant is lost, the humectant will absorb moisture from the sealed space formed by the cap and the ink nozzle face when the ink nozzle face is covered by the cap, thus accelerating evaporation of moisture from the ink nozzles and promoting increased ink viscosity. As a result, the ink nozzles become easily clogged.
To prevent this from happening, Japanese Unexamined Patent Appl. Pub. JP-A-2009-226719 teaches an inkjet printer that has a moisture supply mechanism to supply moisture into the cap. The moisture supply mechanism in JP-A-2009-226719 has a moisture tank, a moisture discharge head with a fluid nozzle face in which a fluid nozzle for discharging moisture is formed, a moisture supply path that connects the moisture tank and the fluid nozzle, and a suction pump. When the fluid nozzle face is covered by the cap, the suction pump produces negative pressure in the sealed space formed between the cap and the fluid nozzle face, and forcibly discharges moisture supplied from the moisture tank from the moisture discharge head to the cap.
The moisture supply mechanism described in JP-A-2009-226719 does not require a mechanism that ejects moisture into the moisture discharge head itself. Moisture can also be discharged from the moisture discharge head using the suction pump that is used for the ink suction operation. The cost of manufacturing an inkjet printer with the moisture supply mechanism can therefore be suppressed. However, leakage of moisture from the moisture discharge head or backflow of the moisture in the moisture supply path could occur depending on the location of the moisture tank. If the moisture leaks, the inside of the printer could become wet. If moisture backflow occurs, the amount of moisture discharged into the cap by the suction operation of the suction pump will be unstable, and the moisture level inside the cap cannot be kept at the desired level.
If a part with a small diameter is formed in the fluid nozzle, the moisture can be prevented from leaking or backflowing by the pressure resistance of the meniscus of the moisture in the fluid nozzle. However, if the diameter of the fluid nozzle is on the order of several ten microns, a hydraulic head of several hundred millimeters cannot be withstood, manufacturing the moisture discharge head is therefore more difficult, and the product manufacturing cost increases.